Caveman — Jeffrey W. Tenney

Trent Marshall, an American archaeologist, enters a mysterious cave in eastern France and is unexpectedly transported back in time to 40,000 B.C.E. With him is a talented and beautiful linguist, Bridgette Genet. At once they find themselves in the middle of a small-scale “war” between the dominant Cro-Magnon tribe and the hill-dwelling Neanderthals.